Official government estimates put the cost of carbon pollution at $21 per ton of carbon dioxide (CO2), says Johnson. But the new study faults the government estimates “for relying upon discount rates that are considered too high for intergenerational cost-benefit analysis, and for treating monetized damages equivalently between regions, without regard to income levels.” Johnson and Hope place the cost between $55 and $266 per ton, although Johnson cautions that “even these revised estimates may be too low,” as “they correspond to what might happen if future temperature increases are in the middle of scientists’ projections – not any of the worse-case scenarios they warn us about.”

The faulty government damage estimates have potentially serious consequences in terms of policy[8]. Johnson writes that “The government’s approach matters a lot because its numbers are used to decide what actions should be taken now to fight climate disruption, such as the choice of what type of electric power[9] we should build, which would change if more accurate estimates were used.”